1. Field of the Invention
The present invention relates to a board for a stringed instrument, a method of manufacturing a board for a stringed instrument, and a stringed instrument.
Priority is claimed on Japanese Patent Application No. 2013-219355, filed on Oct. 22, 2013, the content of which is incorporated herein by reference.
2. Description of Related Art
Front and back plates of a violin have partially different thicknesses so as to obtain satisfactory acoustic characteristics and have a unique camber shape of being gently curved to be convex toward a front or back surface side thereof. Front and back plates used in a viola, a cello, and a double bass belonging to the violin family also have a camber shape having partially different thicknesses as in the case of a violin.
In the related art, during the manufacture of front and back plates of the violin family, a solid wooden block is cut or carved to be formed in a camber shape having partially different thicknesses. However, when a solid wooden block is cut to manufacture front and back plates, there are problems in that time and labor are required due to a significantly large number of cutting processes, and the material yield is extremely low at about 10%.
Recently, as front and back plates of the violin family, plates in which a camber shape having partially different thicknesses is formed by press-bending a board having a smaller thickness than a wooden block to partially compress and curve the board have been manufactured (refer to p. 203, “VIOLIN, Instrument Encyclopedia”, published by Tokyo Ongaku-sha).
In addition, front and back plates of the violin family can also be manufactured by laminating a plurality of veneers adhered to each other by an adhesive to obtain laminated wood and bending the laminated wood to be gently curved.
In the front and back plates, since a camber shape is formed by bending, the number of cutting processes for forming the camber shape can be reduced. Accordingly, these front and back plates can be more efficiently manufactured as compared to the plates manufactured by cutting a wooden block, and the material yield is also improved.
However, in the front and back plates formed by press-bending a board, the thicknesses thereof are made to be partially different and a predetermined thickness distribution is formed by partially compressing the board. Therefore, the wood density in the compressed portion increases, and a variation in density is significantly large in the front and back plates. Even if front and back plates of the violin family have a unique camber shape, when a variation in density is large, a vibration during playing is different from the unique vibration of the violin family. Therefore, in a stringed instrument including a front plate and/or a back plate formed by press-bending, satisfactory acoustic characteristics may not be obtained.
In addition, in the front and back plates formed by press-bending, after the manufacture, a thickness distribution and a camber shape thereof are likely to be changed by a restoring force of compressed wood. Therefore, when a stringed instrument including the front and back plates formed by press-bending is used for a long period of time, acoustic characteristics may deteriorate, or there may be a damage caused by deformation of the front plate and/or the back plate.
On the other hand, in the front and back plates in which a camber shape is formed by bending laminated wood, the laminated wood is not partially compressed during the manufacture, and thus a variation in density is small. Accordingly, the above-described problems caused by the density in the front and back plates do not occur.
However, these front and back plates are uniform in thickness. Therefore, in a stringed instrument including these front and back plates, a vibration of the front and back plates during playing is different from the unique vibration of the violin family, and satisfactory acoustic characteristics may not be obtained.
In addition, there may be a case where a camber shape having partially different thicknesses is formed by press-bending laminated wood. However, in this case, since the laminated wood is partially compressed by press-bending, a variation in density is large in the front and back plates.
In addition, there may be a case where a camber shape having partially different thicknesses is formed by cutting laminated wood before or after bending the laminated wood. However, when the laminated wood is cut, a laminated cross-section is exposed to the surface, and a good appearance cannot be obtained.